| Structural highlights
Function
MRP4_HUMAN ATP-dependent transporter of the ATP-binding cassette (ABC) family that actively extrudes physiological compounds and xenobiotics from cells. Transports a range of endogenous molecules that have a key role in cellular communication and signaling, including cyclic nucleotides such as cyclic AMP (cAMP) and cyclic GMP (cGMP), bile acids, steroid conjugates, urate, and prostaglandins (PubMed:11856762, PubMed:12523936, PubMed:12835412, PubMed:12883481, PubMed:15364914, PubMed:15454390, PubMed:16282361, PubMed:17959747, PubMed:18300232, PubMed:26721430). Mediates the ATP-dependent efflux of glutathione conjugates such as leukotriene C4 (LTC4) and leukotriene B4 (LTB4) too. The presence of GSH is necessary for the ATP-dependent transport of LTB4, whereas GSH is not required for the transport of LTC4 (PubMed:17959747). Mediates the cotransport of bile acids with reduced glutathione (GSH) (PubMed:12523936, PubMed:12883481, PubMed:16282361). Transports a wide range of drugs and their metabolites, including anticancer, antiviral and antibiotics molecules (PubMed:11856762, PubMed:12105214, PubMed:15454390, PubMed:17344354, PubMed:18300232). Confers resistance to anticancer agents such as methotrexate (PubMed:11106685).[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]
Publication Abstract from PubMed
BACKGROUND: ABCC4 (ATP-binding cassette sub-family C member 4) is a transporter protein that is primarily localized to the plasma membrane, and its efflux activity is associated with the progression of various cancers and the development of drug resistance. Cyclic adenosine monophosphate (cAMP) is an important biomolecule that is considered a transport substrate of ABCC4. However, there is currently no direct structural understanding of how ABCC4 binds cAMP, and the mechanisms by which it recognizes a diverse range of substrate ligands remain poorly understood. Some studies have indicated that, under physiological conditions, cAMP does not significantly stimulate the ATPase activity of ABCC4, making the commonly used ATPase activity assays for ABC proteins unsuitable for studying cAMP. RESULTS: Here, we successfully resolved the cryo-electron microscopy (cryo-EM) structure of the human ABCC4-cAMP (hABCC4-cAMP) complex, revealing how hABCC4 binds to cAMP and identifying the key residues involved. This structure was compared with two other hABCC4 complex structures we obtained (Methotrexate and Prostaglandin E(2)) and with previously published structures. We discovered some new structural insights into how hABCC4 binds ligands. On the basis of the structural information obtained, we confirmed the feasibility of using 8-[Fluo]-cAMP in a transport assay to detect cAMP translocation and found that some challenges remain to be addressed. CONCLUSIONS: These results suggest that hABCC4 can bind cAMP and exhibits varying degrees of flexibility when binding with different substrates, including cAMP. These findings expand our understanding of the structural biology of ABCC4.
Structural basis of human ABCC4 recognition of cAMP and ligand recognition flexibility.,Wen X, Si K, Zhu D, Zhang A, Guo C, Li M, Tian W Cell Biosci. 2025 Mar 27;15(1):39. doi: 10.1186/s13578-025-01377-y. PMID:40148998[14]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Lee K, Klein-Szanto AJ, Kruh GD. Analysis of the MRP4 drug resistance profile in transfected NIH3T3 cells. J Natl Cancer Inst. 2000 Dec 6;92(23):1934-40. PMID:11106685 doi:10.1093/jnci/92.23.1934
- ↑ van Aubel RAMH, Smeets PHE, Peters JGP, Bindels RJM, Russel FGM. The MRP4/ABCC4 gene encodes a novel apical organic anion transporter in human kidney proximal tubules: putative efflux pump for urinary cAMP and cGMP. J Am Soc Nephrol. 2002 Mar;13(3):595-603. PMID:11856762 doi:10.1681/ASN.V133595
- ↑ Adachi M, Sampath J, Lan LB, Sun D, Hargrove P, Flatley R, Tatum A, Edwards MZ, Wezeman M, Matherly L, Drake R, Schuetz J. Expression of MRP4 confers resistance to ganciclovir and compromises bystander cell killing. J Biol Chem. 2002 Oct 11;277(41):38998-9004. PMID:12105214 doi:10.1074/jbc.M203262200
- ↑ Zelcer N, Reid G, Wielinga P, Kuil A, van der Heijden I, Schuetz JD, Borst P. Steroid and bile acid conjugates are substrates of human multidrug-resistance protein (MRP) 4 (ATP-binding cassette C4). Biochem J. 2003 Apr 15;371(Pt 2):361-7. PMID:12523936 doi:10.1042/BJ20021886
- ↑ Reid G, Wielinga P, Zelcer N, van der Heijden I, Kuil A, de Haas M, Wijnholds J, Borst P. The human multidrug resistance protein MRP4 functions as a prostaglandin efflux transporter and is inhibited by nonsteroidal antiinflammatory drugs. Proc Natl Acad Sci U S A. 2003 Aug 5;100(16):9244-9. PMID:12835412 doi:10.1073/pnas.1033060100
- ↑ Rius M, Nies AT, Hummel-Eisenbeiss J, Jedlitschky G, Keppler D. Cotransport of reduced glutathione with bile salts by MRP4 (ABCC4) localized to the basolateral hepatocyte membrane. Hepatology. 2003 Aug;38(2):374-84. PMID:12883481 doi:10.1053/jhep.2003.50331
- ↑ Sauna ZE, Nandigama K, Ambudkar SV. Multidrug resistance protein 4 (ABCC4)-mediated ATP hydrolysis: effect of transport substrates and characterization of the post-hydrolysis transition state. J Biol Chem. 2004 Nov 19;279(47):48855-64. PMID:15364914 doi:10.1074/jbc.M408849200
- ↑ Van Aubel RA, Smeets PH, van den Heuvel JJ, Russel FG. Human organic anion transporter MRP4 (ABCC4) is an efflux pump for the purine end metabolite urate with multiple allosteric substrate binding sites. Am J Physiol Renal Physiol. 2005 Feb;288(2):F327-33. PMID:15454390 doi:10.1152/ajprenal.00133.2004
- ↑ Rius M, Hummel-Eisenbeiss J, Hofmann AF, Keppler D. Substrate specificity of human ABCC4 (MRP4)-mediated cotransport of bile acids and reduced glutathione. Am J Physiol Gastrointest Liver Physiol. 2006 Apr;290(4):G640-9. PMID:16282361 doi:10.1152/ajpgi.00354.2005
- ↑ Ci L, Kusuhara H, Adachi M, Schuetz JD, Takeuchi K, Sugiyama Y. Involvement of MRP4 (ABCC4) in the luminal efflux of ceftizoxime and cefazolin in the kidney. Mol Pharmacol. 2007 Jun;71(6):1591-7. PMID:17344354 doi:10.1124/mol.106.031823
- ↑ Rius M, Hummel-Eisenbeiss J, Keppler D. ATP-dependent transport of leukotrienes B4 and C4 by the multidrug resistance protein ABCC4 (MRP4). J Pharmacol Exp Ther. 2008 Jan;324(1):86-94. PMID:17959747 doi:10.1124/jpet.107.131342
- ↑ Janke D, Mehralivand S, Strand D, Gödtel-Armbrust U, Habermeier A, Gradhand U, Fischer C, Toliat MR, Fritz P, Zanger UM, Schwab M, Fromm MF, Nürnberg P, Wojnowski L, Closs EI, Lang T. 6-mercaptopurine and 9-(2-phosphonyl-methoxyethyl) adenine (PMEA) transport altered by two missense mutations in the drug transporter gene ABCC4. Hum Mutat. 2008 May;29(5):659-69. PMID:18300232 doi:10.1002/humu.20694
- ↑ Miah MF, Conseil G, Cole SP. N-linked glycans do not affect plasma membrane localization of multidrug resistance protein 4 (MRP4) but selectively alter its prostaglandin E2 transport activity. Biochem Biophys Res Commun. 2016 Jan 22;469(4):954-9. PMID:26721430 doi:10.1016/j.bbrc.2015.12.095
- ↑ Wen X, Si K, Zhu D, Zhang A, Guo C, Li M, Tian W. Structural basis of human ABCC4 recognition of cAMP and ligand recognition flexibility. Cell Biosci. 2025 Mar 27;15(1):39. PMID:40148998 doi:10.1186/s13578-025-01377-y
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